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astroengine writes "On Friday, the Extrasolar Planets Encyclopedia registered more than 700 confirmed exoplanets. Although this is an amazing milestone, it won't be long until the 'first thousand' are confirmed. Only two months ago, the encyclopedia — administered by astrobiologist Jean Schneider of the Paris-Meudon Observatory — registered 600 confirmed alien worlds. Since then, there has been a slew of announcements including the addition of a batch of 50 exoplanets by the European Southern Observatory's High Accuracy Radial velocity Planet Searcher (or HARPS) in September."

I just spend the weekend at a family gathering. Many of my relatives are doctors, scientists, and professors. The topic of alien life came up, and almost all of them laughed it off! Now I'm merely a computer programmer so I didn't say much, but when I hear about there being hundreds of exoplants out there in space I can't help but think that there may be life on at least some of them. After all, these are only the planets that we know about so far! There are probably millions upon millions of other similar planets out there that we just haven't discovered yet.

Why do well-educated scientists consider alien life, even if it's very simple or nothing like life here on earth, to be such an absurd idea? Why do they have so much trouble considering it with any seriousness?

Because if what we've found so far is at least a somewhat representative sample, the overwhelming majority of planets tend to be either gas giants, frozen balls of rock and ice, or roasted balls of rock and lava. You have to be terribly imaginative to see life coming up on worlds like that.

Of course, even if we go by 1 in 700, or 1 in a million for that matter, the Milky way ought to be positively teeming with life. We simply don't have enough data to make a meaningful conclusion either way yet.

The problem is that many of those gas giants are close to their stars, and that doesn't bode well for finding habitable terrestrial planets. Gas giants can't form close to stars, they have to migrate towards them.

We can restate the original premise. Our methods are biased towards finding large planets close to stars.

Given the limits of our current techniques, it should be possible to quantify the limits of their resolution. Put this together with some models of solar system formation and we can extrapolate our observations using a model that says X% of all planetary discs tend to evolve into systems with large planets that migrate in toward their sun. So 1-X remain in some other state. perhaps one we can't detect (yet).

For some methods fully confirming a planet requires more than one orbit. Their orbit may be measured in years, decades or centuries. For other methods it's a one off event and we can't confirm the existence of the planet. The first confirmed planets were detected around a pulsar (a kind of dead star) only in 1992. And the method used only worked for pulsars. It took until 1995 to detect a planet around a main sequence star.

Then it took years to get dedicated space instruments up. Effectively we've been at this only for 17 years. Given the difficulty that's nothing. Give it time! Perhaps your grandkids will grow up with earth sized planets confirmed.

Not to mention objects with really short orbits, which means much more rapid observations. Any planet will only pass between the star and us once per cycle (assuming it's in the plane) which makes it much easier to find orbits measures in weeks or months instead of years and decades. Like for example our Jupiter has an orbit of almost 12 years. They need two measurements to get a period and want three for confirmation, that's 36 years. How long have we been searching for exoplanets again? Oh right, we wouldn't have found our own solar system yet.

"Because if what we've found so far is at least a somewhat representative sample, the overwhelming majority of planets tend to be either gas giants, frozen balls of rock and ice, or roasted balls of rock and lava. You have to be terribly imaginative to see life coming up on worlds like that."

There are plenty of life forms that live in unusual environments right here on this planet. Geothermal vent ecosystems for example:

Deep-sea bacteria form the base of a varied food chain that includes shrimp, tubeworms, clams, fish, crabs, and octopi. All of these animals must be adapted to endure the extreme environment of the vents -- complete darkness; water temperatures ranging from 2C (in ambient seawater) to about 400C (at the vent openings); pressures hundreds of times that at sea level; and high concentrations of sulfides and other noxious chemicals.

I just spent my last mod point 30 seconds ago...This guy got modded up telling an anecdote implying that scientists laugh off the idea of alien life?Parents answer is most concise: this is just not the case....Sigh...

Well, actually, at the latest AAS meeting there was a talk by an expert who said that they now have enough statistics to know that one in ten stars has a gas giant and one in three has a rocky planet similar to Earth or Mars. This is from memory so excuse me if I am slightly off or swapped the numbers. They openly said that they are looking for methods to detect planets capable of having life (i.e. water, CO2, etc).

I guess we are at the point in time where an expert on exoplanet searches knows that findin

Why do well-educated scientists consider alien life, even if it's very simple or nothing like life here on earth, to be such an absurd idea? Why do they have so much trouble considering it with any seriousness?

The scientists in your family may not be representative of scientists in general.

I've always assumed that most people who know the numbers involved think that alien life must exist (with a hundred billion stars per galaxy and hundred billion galaxies, it seem like there are pretty good odds).

Whether we'll communicate with, travel to, or be visited by aliens is an entirely different question with a lot more scope for doubt.

I've always assumed that most people who know the numbers involved think that alien life must exist (with a hundred billion stars per galaxy and hundred billion galaxies, it seem like there are pretty good odds).

Part of the problem is that some people use 'alien life' to mean anything from microbe-sized upwards while others use it to mean 'little grey men in flying saucers'. The former is almost certain to exist, but there's no evidence for the latter and good reason to believe that they don't exist; technology merely a few thousand years ahead of ours should be visible across much of the galaxy.

That's not really good reason to believe they don't exist. A galactic spanning civilization, for one, would only be visible, as you say, across the galaxy. Not across the entire universe. And secondly, as of right now it is only a pipe dream that a couple thousand more years of history will spread us across the stars. We might just as easily blow ourselves up, retreat into a cyber-singularity, or just run out of gas, so to speak.

But anyway, I agree that it's likely that microbial life of various sorts is abundant. And on the other end, I've always felt that it is only a kind of cellular chauvinism that prevents us from thinking of stellar objects as life forms. They grow, they mantain homeostasis, they sometimes reproduce in a fashion, they consume, they die.

That's not really good reason to believe they don't exist. A galactic spanning civilization, for one, would only be visible, as you say, across the galaxy.

That's not obviously the case. Largescale stellar engineering is something we might notice. Dyson Spheres and Ringworlds for example are both things that we'd be able to see in nearby galaxies. Similar remarks apply to other big engineering projects.

But anyway, I agree that it's likely that microbial life of various sorts is abundant. And on the other end, I've always felt that it is only a kind of cellular chauvinism that prevents us from thinking of stellar objects as life forms. They grow, they mantain homeostasis, they sometimes reproduce in a fashion, they consume, they die.

By this logic fire would be alive also. Stars don't seem to do much of the things that life does, in particular, stars don't reproduce in a way that makes stars more similar to themselves than not so (except in so far as high metal content supernova lead to even

How would we see a Dyson Sphere if it's capturing all the output from their star? It would be just another patch of blackness against the inky black of space. Our small slice of space we can view at any given time is very tiny, frequently changing, and we can't actually see most of these exoplanets, just their effect causing their stars to wobble. We'd have no hope of seeing satellites around a planet, or space shuttles, or even a space ship the size of one of the Alliance citadel style things in Firefly

IANAA but as I understand it a Dyson Sphere should have a pretty big infrared signature and (probably) not much in the way of other emissions. This is because if all of the contained star's energy output is being captured and used then the waste product (i.e. heat) has to be dumped somewhere (namely outside the sphere). Not sure how one would detect a ringworld though...

How would we see a Dyson Sphere if it's capturing all the output from their star?

Captures and then does what with it? None can fool Second Law of Thermodynamics. In order to use some, you have to let some go, or else there is no flow of energy. A Dyson Sphere would most certainly shine with brightness comparable to its star.

It would output the same energy as the star but would have a vastly greater surface area than the star, so the energy density would be much less. It would only radiate in the infrared and very hard to detect.

The existence of extraterrestrial life is completely philosophical and hypothetical. Saying that such-a-such scientist does or does not think there is otherworldly life is not proof one way or another, even if that scientist is decorated or the great Hawking, whom I admire. We can discuss the size of the universe, the number of stars and discuss it from a statistical point of view. The math involved does lead to the probable conclusion that extraterrestrial life must exist, but this is again not proof.
As

There are more practical issues - our technological age of reason isn't actually very old yet.

Take SETI and radio transmissions - we've only been emitting radio for 200 years, and we're rapidly confining the emissions or ditching them entirely (fiber optics). Who's to say that within the next, 50 years or so we won't discover some alternate broadcast technology which dispenses with radio entirely? (entangled particles come to mind, if communications by that route were ever to be possible).

You can see the reason for moving off Earth quite easily. Lots of people believe that the idea of a growing economy is a false promise because the Earth is a closed system and will run out of... well, everything... eventually. So the "answer" to these people is to contract everything down into a "sustainable" way of life for as many humans as possible. Sure, they will be living in mud huts, but hey, it will be sustainable and as long as there is no growth it will be able to continue forever.

It's also possible that numerous civilisations with a similar level of technology to ours exist, but it's simply impossible in practice to "colonise the galazy". Inter-stellar travel may simply require too much energy/resources, or it may turn out to be infeasible to survive in space for long enough for anybody to reach another star.

The Fermi paradox though is that it would only take one bug eyed monster with the stubbornness (and longevity) to hop on the slow boat to Proxima Centauri, then it's just a matter of time before the Milky Way gets colonised. Even at sublight speeds, the BEM could do it in under a billion years.

Scott Adams explains it away in The Dilbert Principle though - the holodeck will be our last invention ever. If you can simulate it, why go to the expense and risk of actually doing it?

This. I think the conclusion that any sufficiently advanced civilization is fully "computerized" is inevitable; once you have the technology, there's simply no (rational) reason not to abandon your meatbag and migrate to a more robust and easily maintained container.

technology merely a few thousand years ahead of ours should be visible across much of the galaxy.

Why do you assume that? Maybe other forms of life don't use technology the way we do. Maybe they choose to use non-broadcast forms of technology. Maybe their communications tech has moved well beyond anything we've yet discovered, i.e., people using radios are going to be invisible to people looking for smoke signals. Maybe the galaxy is populated by planet-eating space goats that are attracted to coherent electromagnetic transmissions, and wise civilizations have learned not to broadcast. There can b

Were they laughing off the idea of extraterrestrial life itself, or the stuff you commonly see in popular culture...you know, the people who treat Roswell like a Mecca, go on about grays and abductions and crop circles, anyone who agrees with Ancient Aliens Guy [youtube.com], ect.? It is one thing to speculate that, out of countless stars, it is possible that there exists more than one planet with some sort of life (while admitting that there is no evidence whatsoever to indicate that that is the case and acknowledging

Just speculating that the context of the discussion matters a lot. Maybe they felt a lot of peer pressure to discredit the idea, since they were all together. Or it could be that they are sick of real kooks talking about aliens. "Aliens" is different than "life". Aliens is Sigourney Weaver.

A relative of mine worked at an public observatory/science center for many years in a big city. He had to deal with a lot of loonies who know what flavor of ice cream the aliens like. Many feel a very religious connecti

They aren't computer scientists, or perhaps they'd have a different attitude. It takes shockingly little in the way of logic to create the equivalent of a Turing Machine. Just NAND gates are enough. Are we a superior kind of computer? Do we possess to ability to solve some problems faster, algorithmically faster that is, than a computer could? Is a Turing Machine incapable of duplicating a living creature? I think the answer to all those questions is no. I expect that there are many environments that

Why do well-educated scientists consider alien life, even if it's very simple or nothing like life here on earth, to be such an absurd idea? Why do they have so much trouble considering it with any seriousness?

They are aware that of the lack of evidence for alien life? It seems to me that your relatives understand the difference between science and science fiction while you do not.

There is a difference between putting forward a hypothesis that life "might" exist on other planets given the right conditions and believing that alien life "must" exist.

Scientists ultimately have to deal with facts and even test theories against real observations. Their rational approach is what separates scientists from science "enthu

Anyway, we really have no idea what's out there. The Drake equation has been criticized for being of little use; what it does very well though is point out how much we don't know. The great thing though is that we're progressing very rapidly; if life (not necessarily intelligent) is rather common, we will find out in less than 3 decades, possibly earlier. The upcoming 30m and up telescopes are getting close to the point where we could do spectral anal

Were you talking about extraterrestrial life in general or extraterrestrials visiting earth? Some people assume when you are talking about aliens you are talking about the big-headed Grays flying in UFOs. That's alot different than talking about single cell organisms on a planet 20 light years away. Also, many educated people who aren't in astronomy have no clue about just how big the Universe is. I think if they are shown just how many stars exist and how many probably have planets, they can be shown that

There are scientists and there are scientists. If the scientists in your family scoff at the idea of alien life then their opinions may not have been well considered. There are plenty of very credible thinkers who feel quite certain that we will one day find life off the earth - Stephen Hawking among them.
People who scoff at ideas which seem far fetched just because they seem far fetched have a history of looking quite red faced when later they turn out to be wrong. The earth is flat and the centre of the

Imagine a large city. Imagine within this city, a smaller city, in a dome which is visually opaque, but completely open to all other electromagnetic spectra.

Plop a scientist from, say, the 1800s into that domed city. Ask him to prove the existance of life outside the dome based on communications. Is he going to be able to intercept and decode NTSC? ATSC? 802.11b/g/n? CDMA? GSM? Hell, AM and FM?

The Fermi paradox asks why people aren't just wandering into his dome. Sooner or later, surely someone is going to walk in off the outside street, right? Or at least knock on the door. Heck, even a scientist from the 1800's could conclude that the dome is an artificial structure surrounding him. He'd be able to detect trucks and subways going by outside, hear jets overhead, etc. All weird, inexplicable phenomena that clearly aren't natural. We've seen nothing like that out in the universe so far.

Hey, I never said the analogy was perfect. All I'm saying is that a) absense of evidence is not evidence of absense, and b) given that even a hundred years ago, radio communication was considered a pipe dream, flight was considered a pipe dream, and so on, we shouldn't assume we're equipped to find extraterrestrial life.

a) absense of evidence is not evidence of absense b) given that even a hundred years ago, radio communication

The Fermi paradox isn't saying "there are no aliens", it is asking "why aren't we seeing aliens in any form?"

Your explanation is "because they are using communications technologies we can't detect". But that doesn't address the paradox. The paradox asks: (1) why aren't they physically here and (2) why don't we detect their activity?

Why aren't we seeing them? Or why aren't we capable of seeing them? We're just now, as a whole, beginning to take seriously the idea that 'life' could mean something other than 'earth like planet in the golidlocks zone of a star.' With the discovery of extremeophiles, the idea of arsenic-based life, and so on, we're getting the idea that we might not be looking for non-earth-based earthlings. "Where are they?" Who knows. "Why aren't we seeing them?" Well, maybe we're not looking for them. Same reaso

I think you don't quite understand what the Fermi paradox is about. There may be lots of intelligent, sub-glacial pond scum, but that's not what the Fermi paradox isn't concerned with their existence.

The Fermi paradox is essentially: why can't we detect a single civilization like ours: oxygen atmosphere, technology use, energy use, the whole bit? Given that it took less than a billion years to go from nothing to humanity, that there are lots of stars like ours, lots of planets, and organic chemistry provi

Because given what we already know about physics and the universe, the distances are not a problem. All you need is the ability to colonize objects like asteroids and comets, and even humans are close to that. Time, reproduction, and galactic rotation will do the rest. It takes maybe a few hundred million years to spread across the galaxy.

Get some perspective on humanity and biology and get out of your Buck Rogers and Christian mindset: the Earth wasn't created 6000 years ago, and the apocalypse and end time aren't near. Intelligent life on this planet has many millions of years ahead. People will settle in space not for short term economic reasons (which is what the Economist and Savage debate), but simply because they can and they get bored here.

We have neither the technology or energy resources to do what you want. Ever.

Launching a large, self-sustaining inflatable habitat takes a few launches using existing technologies and rockets. There's no technology or energy needed beyond that. Once launched, traveling anywhere in the solar system (and beyond) takes essentially no energy if you go slowly, and there is no reason to go fast.

And when the oil starts getting more and more expensive, what will power your precious rockets?

When Kepler's planets are confirmed (I guess when it sees 3 or more transits), I think this total will more than double.

Also, I don't know where the AC above is coming from but the scientists I know (tenured theoretical chemist who worked under a Nobel laureate, computational linguist who's father won a fields medal, A.I. expert funded by DARPA and prominent computer graphics researcher with 9 patents) all think it is very VERY likely there is life out there. (Are the AC's acquaintances in the "hard" scien

What is wrong with skepticism? What is wrong with saying " I don't know " ? I recommend reading Peter Ward's " Rare Earth " . Given the Over-abundant research and data listed in that book, i would say Khipu is rather spot on. Listing the fact that you " Know Scientists " is rather like living in LA and saying you " know some famous people". None of the ones listed in your references are specialists the Astronomical or Geological sciences. I would like to say that, yes, possibly a good chance exists when yo

Look, my friends said it is very very likely not that it was 100% sure (they are scientists after all!). I mean that's a very reasonable stance to take considering that there are about a 100 billion stars in our galaxy, and about a trillion stars in the OBSERVABLE universe (the actual universe is likely to be MUCH larger, maybe infinite). Considering the large proportion of stars that seem to have planets and the billions of years they've been around it, doesn't it seem very VERY likely that life would have started more than once?

Flip a coin several trillion times. What's the chance that it won't come up heads more than once?

Of course I've read "Rare Earth" AND his other book "Life, But not as we know it" in which he says life could've arisen not just on earth but on Mars, Europa, Enceladus and maybe THREE TIMES on Titan! So while he is (rightfully) concerned that COMPLEX life is "rare" (but not impossible) he also seems to think that (simple) alien life is present almost everywhere!

Also, my chemist friend is in the geological sciences dept. of his university and works with experts in the fields of extremeophiles. As for the others, please realize that science is not a vacuum, at least not at the level that they practice it and they follow major developments in other fields both directly and indirectly; they, to varying degrees, have an excellent idea as to what's going on. (My computational linguist friend probably knows the details of the transit studies, he's the kind of guy who learned a difficult Asian language on his spare time while raising a couple kids while developing algorithms so sophisticated he has to give the state dept. one month advance notice before leaving the country).

Actually I'm beginning to think that the people who claim that their educated brethren say that we are unique have their own, belief based, agenda to push. Whatever.

If you believe the geological models of the rise of life on Earth, I find it very telling that life came about so rapidly.

3.8 billion years ago, the earth was probably still molten rock.

Sometime after that, water started to condense on the surface.

3.5 billion years ago, we find fossils for single cellular life. The surface temperature was still high, there was still much exposed molten lava, the day was only 15 hours, radiation blasted the surface incessantly... but life existed in only the first 0.5% of t

Now, complex life... no idea. There's no way to know how rare that actually is.

Well, going with the same logic, didn't the cambrian explosion happen about 500Mya? And couldn't you combine that with a model of how long a planet stays habitable for? Still only one somewhat tenuous data point though. Wonder what other approaches one could take.

Upon reading some other posts I realize that maybe you are not as literal minded as I am (scientists tend to also be very literal minded).

I hope you'll agree that simple life is likely in the cosmos. That may not be what you meant.

Complex life, like Peter Ward said, may be very rare (though I think he's backed off a bit if only because, as he says, simple life may be everywhere). I hope he's wrong but what can I say? Reasonable people may disagree.

oh i am with you on this. The fact that i plugged Ward's book suggests that i agree with his ideas and hypothesis concerning microbial life being relatively abundant. Getting back to the main topic- Discovery of Exo-planets- it is useful in the sense of mapping charts but the usefulness and need to somehow relate this toward life elsewhere in the universe is rather moot as we possess not the means to travel to or instruments to measure it with what we currently possess and where we are located in the cosmos

Younger Slashdot readers cannot imagine what the discovery of exoplanets means to those of us who have been reading science fiction since the 1950s. We dreamed of traveling to the moon, and we managed that thanks to a martyred President. With that milestone accomplished, we looked forward to the planets and the stars.

Somehow, we lost the will to explore space. The Space Shuttle, which should have preceded the exploration of the Moon, was funded only after many compromises, and the program is now ended.

We could put a probe into the Alpha Centauri system within 50 years without question. Sure, launch in 10 years and it takes 40 years to get there. It might be pretty large but it could be assembled in orbit and launched from there.

The only possible justification at this point for not sending such a probe is a rather weak argument that (a) we wouldn't learn anything by doing it and (b) in 46 years we will have advanced sufficiently that we can make it at lightspeed.

Or was the discussion about UFO's and aliens landing and probing peoples' rectums? That would pretty much deserve derisive laughter.They certainly won't show up with anal probes.

I wouldn't be so sure. If aliens did have the technology to visit our planet, why wouldn't they want to grab a few specimens, take us apart and see how we worked? After all, we do the exact same thing to every new organism we come across. Sure, some of them may have tech so advanced they can just point a scanner at us without us